It is now a wide-spread practice to encode data such as product identification on the labels of commericial items using a set of parallel lines ("bars") of varying thickness. This scheme, commonly called a bar code, exploits the relative bar width and/or the spacing between bars to code the data.
In the prior art it is known to optically read bar codes with a hand-held scanner known as a bar code reader. Different types of bar code readers are known in the art, usually including a light source to illuminate the bar code pattern, and a detector to receive light reflected from the bar code. One approach used in the prior art is the "flood light" system, in which one or more light sources illluminates a large area (generally wider than several bars) causing light to be reflected back onto a detector. By employing lenses and/or aperatures, it is provided that only light reflected from a desired point on the bar code will be received by the detector. U.S. Pat. No. 3,784,794 shows a bar code reader of the flood light type. This type of system tends to be inefficient since much of the emitted light is not transmitted to the detector and is therefore wasted.
Another type of optical bar code reader known in the prior art uses fiber optic bundles to transfer light from a source to the bar code and to transfer reflected light back to a detector. These devices use costly fiber optics and also tend to be difficult to assemble and align.